Exercise in childhood can prevent osteoarthritis in knees

ELEANOR HALL: Scientists at the Menzies Research Institute in Hobart have found that your activity as a child can prevent you from developing osteoarthritis later in life.

A 20-year study of almost 300 children around Australia has found that those who did lots of jumping, running and skipping had more cartilage in their knees than those who were sedentary.

The Australian researchers are presenting their findings today at a conference in the United States, as Felicity Ogilvie reports.

(Sound of walking on stairs)

FELICITY OGILVIE: Sixty-seven-year-old Paddy Barbour is walking up the stairs.

He used to take them two at a time or run but he can't do that anymore because he has osteoarthritis in his knees.

PADDY BARBOUR: I was always very active, very outdoors, and I retained that activability into my 67th year. It's only for the last sort of 18 months, two years that I'm starting to feel twinges in the knees.

FELICITY OGILVIE: Mr Barbour is not alone in his aches and pains - almost one in five Australians has arthritis.

But doctors at the Menzies Research Institute in Hobart have found that active children are less likely to go on to develop osteoarthritis in their knees.

Professor Graeme Jones says that's because children's knees get stronger when they exercise.

GRAEME JONES: The bones adapt to that extra physical load and because cartilage basically covers the end of the bone, if your bone gets larger, you'll grow more cartilage over the end of that bone, so that then gives you a knee that's able to adapt better in later life and should last longer because you've got to lose a fair bit of cartilage before you get end-stage arthritis.

FELICITY OGILVIE: The findings are based on a national study of the health and fitness of children that started in 1985.

Professor Jones says that high impact activities like running, jumping and skipping were more effective in building strong knees than gentler activities like walking.

GRAEME JONES: The more active we make our children the better and the problem of course is that in 1985 most children were active and not overweight, but in 2012 that's a very different story. Most children are actually inactive and there's a lot more childhood obesity. So I expect this to have an impact on what happens to knee arthritis in later life.

FELICITY OGILVIE: Professor Jones says the ideal age for children to be developing their knee strength through exercise is before they hit puberty.

But he says it's still possible for adults to grow new cartilage.

GRAEME JONES: It used to be thought that you couldn't change the amount of cartilage you had after 18 but it now looks like that number's gone up to about 45.

ELEANOR HALL: Still hope there then. Professor Graeme Jones from the Menzies Research Institute.